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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS</title>
    <link rel="stylesheet" href="./select.css">
    <style>
        span {
            background-color: blue;
        }
    </style>
</head>
<body>
    <h1 class="title">一级标题</h1>
    <p>段落中</p>
    <ul>
        <li>第一</li>
        <li>第二</li>
        <li>第三</li>
        <li>第四</li>
    </ul> 
    <article>
        白鹅白鹅
    </article>
    <span style="color: red;">
        在每个声明里要用冒
    </span>
    <ul class="main">
        <li>1</li>
        <li>
            <ul class="special">
                <li>11</li>
                <ul>
                    <li>111</li>
                </ul>
            </ul>
        </li>
    </ul>



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